A known automobile navigation system functions as follows: when the relevant vehicle is running, it detects the present position by GPS (Global Positioning System) or the like, and displays the present position, together with a road map, on a display device. The system sets appropriate routes from the present position to a destination, and provides routing assistance through the display device or a voice output device. Thus, the automobile navigation systems assist drivers to efficiently drive a car in safety.
In general, the automobile navigation system is not only provided with a basic function of displaying the present position of the relevant vehicle together with the road map of its surrounding area. It is also provided with a function of allowing the user to search for place names or facilities classified by prefectures. In general, this search function is utilized when the user sets a destination, a place on route, or a registered place. More specific description will be given. When the user sets a destination or the like, he/she utilizes the search function to search for a place name or facility, and sets the found place name or facility as the destination or the like. However, this search function has a problem. With this function, the operator can search for his/her desired specific facility, such as a parking lot, but cannot search for areas where a large number of specific facilities are located, for example, districts where parking lots are concentrated.
To cope with this, the navigation system described in Patent Document 1 searches for areas where specific facilities are located based on map information. Further, it displays the degree of concentration of the specific facilities to allow the operator to grasp the degrees of concentration of the specific facilities in the surrounding areas. Thus, when the specific facility is department store, for example, a traffic jam is expected in districts where a plurality of department stores are concentrated. Therefore, the operator can make route search avoiding such districts.                Patent Document 1: JP-2004-109146 A        
In the example found in Patent Document 1, specific facilities in the surrounding area are searched for, and the degree of concentration of the specific facilities in the surrounding area is grasped. Therefore, areas, such as downtowns, where a large number of specific facilities are located cannot be searched for.
As mentioned above, the conventional technologies involve a problem: downtowns where various stores are concentrated cannot be searched for. Recently, there have been users' demands for making a little visit to a downtown to look around a lot of stores, or for learning what stores are located in a downtown. However, it is difficult to meet the demands with the conventional technologies.